You'll need to cut off the tabs and then clean up the remnants. While you can do this with a hacksaw and metal files, it's much more fun to buy a new tool to do both with.
You can either buy an angle grinder or a Dremel.
Personally I would go with a Dremel. I just bought one and it really rocks for cutting and filing jobs. I've cut out my steering head races, tabs off the frame, ground down ugly factory welds, and cut up a seat pan with it.
You can't go wrong with a Dremel purchase.
That's what I did for these kind of chores.....